Transposable element

Transposable elements (TEs), also known as "jumping genes," are DNA sequences that can change their position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Barbara McClintock discovered them during the 1940s and 1950s, for which she was awarded the 1983 Nobel Prize in Physiology or Medicine.

Classification

Transposable elements make up a large fraction of the genome and are often considered junk DNA. They are classified into two main types: Class I TEs or retrotransposons, which are usually copied in RNA and then transcribed back into DNA by reverse transcriptase, and Class II TEs or DNA transposons, which are directly transposed by "cut and paste" or "copy and paste" mechanisms.

Mechanism

The mechanism of transposition includes the excision of the TE from the original site and its reinsertion into a new location. This process can lead to the duplication of the same TE in the genome. The movement of TEs is a driving force of genome evolution as it can cause mutations and change the amount of DNA in the genome.

Impact on Genome

Transposable elements can have profound effects on the genome. They can cause mutations when they insert themselves into genes, disrupting the gene's function. They can also cause DNA rearrangements, leading to changes in the number and location of genes.

See also

• Genetic recombination
• Genetic variation
• Mobile genetic elements
• Molecular evolution

References

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